1. Field of Invention
The present invention relates to an impact attenuator to be connected to a vehicle, and a method to drive such a device.
2. Description of the Prior Art
Impact attenuators are used, at e.g. roadwork areas, to protect road-users, men at work and equipment. The impact attenuators task is to, in a soft way, stop vehicles from entering the roadwork area. This is achieved by an attenuation device that dampens the force of collision from a colliding vehicle by deformation of the construction, e.g. by a metal construction with zones of deformation or an elastical construction of polymeric material.
Common to all impact attenuators are that they during operation are firmly connected to the vehicle to establish a rigid extension of the vehicle. This is because during a collision against the impact attenuator the forces of collision partly shall be absorbed by the vehicle and to prevent the impact attenuator from moving sideways before it has absorbed the major part of the forces.
A usual type of impact attenuator is securely attached to the vehicle and foldable between an operating position and a raised transport position. Another type of impact-attenuating device is disclosed in WO 01/87671 A1. The disclosed impact attenuator has a front member connecting the impact attenuator to a vehicle. The impact attenuator can be connected in a transporting position, through a drawbar, in which the impact attenuator is connected as a trailer to the vehicle, or in an operating position, through two beams, in which the impact attenuator is connected as a rigid extension of the vehicle.
A drawback with both these types of impact attenuators is that they need to change between the operating position and the transport position. This means that there must be equipment for changing between the two positions. Furthermore there is a need for safety arrangements for securing that the impact attenuator is in the right position.